Protective Role of Adhatoda Vasica and Vasicine in Bidi Smoke Induced Cytotoxicity: an Implication for Respiratory Disorders
Total Page:16
File Type:pdf, Size:1020Kb
PROTECTIVE ROLE OF ADHATODA VASICA AND VASICINE IN BIDI SMOKE INDUCED CYTOTOXICITY: AN IMPLICATION FOR RESPIRATORY DISORDERS Synopsis submitted in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY By MAMTA PANT Enrol. No. 09401002 Department of Biotechnology JAYPEE INSTITUTE OF INFORMATION TECHNOLOGY (Deemed to be University u/s 3 of the UGC Act, 1956) A-10, SECTOR-62, NOIDA, UTTAR PRADESH, INDIA July 2016 Synopsis 1 ABSTRACT Tobacco smoking is a major cause of respiratory ailments among both: rural and urban Indians. A large number of toxic chemicals of tobacco smoke are reported to cause various inflammatory diseases by inducing oxidative damage to the exposed biological system. Various natural (majorly from medicinal plants) and artificially obtained medicinal products are in use to combat these inflammatory conditions. Adhatoda vasica is one of the most widely used medicinal plants in Indian traditional system which, is known to treat respiratory ailments. Present study was conducted to investigate if, ethanolic extract of Adhatoda vasica (AVE) and its active phytocompound Vasicine can combat the toxic effects (cell death, oxidative stress and inflammation) induced by bidi smoke concentrate (BSC) in in vitro conditions. As, alveolar epithelial cells are the first ones who get exposed to tobacco smoke during smoking and macrophages are the ones who, neutralize the toxic effect in vivo, human lung alveolar epithelial (A549) and human macrophage (THP-1) cell lines were chosen for this in vitro studies. In order to achieve objectives of this study, the lung cells and macrophages were exposed to AVE (0.125 to 8µg/ml, 3h), Vasicine (0.25 to 6µg/ml, 3h), and BSC (0.5 to 15%, 24h), to determine their safe and toxic doses, respectively. The results have shown that BSC could induce toxicity in both the cell lines in a dose dependent manner. LD50 dose of BSC was found to be 5% and 3%, for A549 and THP-1 cell lines, respectively. Safe ranges for AVE and Vasicine were found to be 1 to 2 and 0.5 to 3µg/ml, respectively, for A549 cell line and 0.5 to 2 and 2 to 3µg/ml, respectively for THP-1 cell line. To investigate the protective potential of AVE and Vasicine, both the cell lines were pre-treated with the optimized safe doses of AVE and Vasicine (1h) and then were exposed to toxic doses of BSC in separate sets of experiments and then examined for various parameters, including cell viability. Among the chosen doses for AVE and Vasicine, 2µg/ml of AVE and 3µg/ml of Vasicine, showed significant protective effect as, both could retain the cell viability (90 ± 0.04% and 89 ± 0.03%, respectively in A549 cell) against 5% BSC. For THP-1 cell line also, 2µg/ml AVE and 3µg/ml Synopsis 2 Vasicine showed significant protective effect as, they could retain the cell viability (87 ± 0.04% and 88 ± 0.03%, respectively) against 3% BSC. It was observed that exposure of A549 as well as, THP-1 cells to BSC, resulted in significant increase in production of superoxide [superoxides (•O2-), through % increase in NADPH consumption, from 11 ± 0.4% (Control) to 53 ± 0.9% (5% BSC) in A549 and from 4 ± 1.9% (Control) to 50 ± 0.9% (3% BSC) in THP-1. Nitric oxide radical production was also observed to be increased by 11 ± 0.32% in A549 and 39 ± 5.7% in THP-1. This treatment also increased the leakage of LDH (lactate dehydrogenase) by 19 ± 0.3% in A549 (5% BSC) and 45 ± 3.7% in THP-1 (3% BSC) cells. Further, studying the status of antioxidants - Superoxide dismutase (SOD) and Catalase (CAT) activity in such a stressed conditions an increase in both the enzyme activities [A549: SOD activity from 9 ± 0.30 U/mg (Control) to 15 ± 0.02 U/mg (5% BSC); THP-1: SOD activity from 29 ± 0.04 U/mg (Control) to 47 ± 0.04 U/mg (3% BSC); A549: CAT activity from 10 ± 0.05 U/mg (Control) to 15 ± 0.04 U/mg (5% BSC); THP-1: 15 ± 0.03 U/mg (Control) to 19 ± 0.04 U/mg (3% BSC)] in the BSC exposed groups were observed. Pre-treatment of cells with optimum safe dose of AVE or Vasicine could maintain these enzymes activities. The integrity of cell membrane and DNA was also maintained by AVE and Vasicine in both the cell lines. Microscopic examination of BSC exposed lung alveolar epithelial and macrophage cells showed cellular apoptotic features such as: blabbed cell membrane, de-shaped nucleus and altered mitochondrial localization and its abundance. Pre-treatment with AVE and Vasicine was observed to prevent these effects. Along with the above observations it was found that treatment with BSC caused an up regulation of pro-inflammatory markers: Tumour necrosis factor-alpha (TNF-α) and Interleukin -6 (IL-6), also in both the cell lines. In this case also, pre-treatment with AVE and Vasicine seemed to reduce the extent of inflammation by down regulating these pro-inflammatory markers. Hence, the findings of this study suggest that bidi smoking exerts considerable negative impact on the cell viability, oxidative state, and expression of pro-inflammatory conditions of both, lung as well as, macrophage cell line. These findings further have Synopsis 3 implications in analyzing the mechanism of respiratory diseases and disorders in people exposed to tobacco smoke. The study suggests that AVE and Vasicine both are able to protect cells from the deleterious effects of tobacco smoke in in vitro conditions. It is thus, propsoed that, both: the ethanolic plant extract and its active compound Vasicine, can further be explored for their exact molecular mechanism of action, so that we can move towards developing their formulations for the management of respiratory disorders caused lined to tobacco smoking. Synopsis 4 Chapter 1 INTRODUCTION Tobacco smoking (TS) is a major risk factor for respiratory diseases. During tobacco smoking, the lung epithelial cells are exposed to the tobacco smoke as a first line and then the toxic material enters into the system [1]. Further, the immune cells present in the alveolar area (alveolar macrophages etc.) and in blood, also get exposed to these toxic substances due to high vascularity of the lung tissues [2]. Normally, immune cells fight back to cope up with the stress induced by the tobacco smoke and in this process they might succeed or else might add to inflammatory phenomena which can ultimately lead to diseased conditions [3]. The present study was conducted to analyze the extent of the toxic effect of Bidi smoke in in vitro conditions, in human lung alveolar epithelial and macrophage (A549 and THP-1) cell lines and to investigate if, the plant Adhatoda vasica and its active phytocompound Vasicine could prevent the toxicity caused by Bidi smoke concentrate (BSC) along with investigating their mechanism of action. 1. Tobacco smoke 1.1 Prevalence and habit of tobacco smoking: Tobacco smoking is popular all over the world and India is a home for approximately 275 million tobacco users [4]. Several means of using tobacco are available in the market and these include cigarettes, cigars, blunts, cigarillos, bidis, chuttas and kereteks. “Bidi” or “beedi” is a slim, hand-rolled, unfiltered cigarette. The bidis are known as the “poor man’s cigarettes”, as these are smaller and cheaper than cigarettes and, are perhaps the cheapest tobacco smoking product in the world. Number of bidis smoked per day, duration of smoking and the age of initiation, are some of the key factors that determine the mortality rate in a tobacco smoking population [5]. 1.2 Chemistry of tobacco smoke: Tobacco smoke (TS) contains around 1015 to 1017 oxidants/free radicals and 4700 other components, including carcinogens, oxidants, reactive aldehydes, quinones, and semiquinones per puff. All of these have the potential to cause inflammation and damage to the cells. Tobacco smoke can be divided into two phases: tar and gas-phase. Both phases contain a large number of reactive oxygen and - nitrogen species (ROS & RNS) like superoxide (·O2 ), hydroxyl (·OH) and peroxyl Synopsis 5 - (·RO2), and RNS like nitric oxide (·NO), nitrogen dioxide (·NO2 ) and peroxynitrite (ONOO-), including phenols and quinine etc. [6]. The toxic compounds and free radicals of tobacco smoke (as discussed above), get absorbed into the blood stream from the respiratory tract from where they reach to various organs of the body like: heart, pancreas, liver and kidney etc. thus, causing toxicity in those organs/tissues [7]. On the other hand, the particles from the particulate fraction of the smoke get adhered to lung tissue and causes injury due to the adhered toxins and oxidant released over hours to days, resulting in progressive cellular injury and mucus membrane destruction. 1.3 Statistical scenario: According to the World Health Organization, tobacco- attributable mortality is projected to increase from 1.5 million deaths in 1990 to 3·0 million annually by 2020 in India [8]. Tobacco-related deaths are projected to increase to more than 8 million deaths a year by 2030 [9]. 2. Respiratory disorders: Lung diseases are some of the most common medical conditions in the world. Tens of millions of people suffer from lung disease in the Unites States every year [10]. Air pollution, smoking, infections, and genetic predisposition are majorly responsible for most of these pathological conditions [11]. Asthma and chronic obstructive pulmonary disease (COPD) are the most common inflammatory lung diseases which are known to be caused by exposure to environmental stressors such as pollution, smoking, UV radiation and dust etc. [12]. Asthma is a chronic inflammatory disorder of the airways characterized by episodes of reversible breathing problems due to airway narrowing and obstruction.